Internet Protocol (IP) data transmission is used extensively in third generation (3G) networks. However, IP-related charging protocols and systems are not necessarily capable of providing all the functionality that would be desirable in a mobile telecommunications scenario. Of particular concern is the wide acceptance and use of pre-paid accounts in relation to mobile telephones. Such prepaid accounts are not dealt with in existing IP-related charging systems, largely because IP-communications are, for the most part, not based on prepaid accounting systems. The problem is exacerbated by the unique nature of the signalling and call set-up routines employed in 3G networks, which have no direct correspondence with, for example, internet access via land-based computers.
A protocol known as Diameter has been proposed for use in IP networks. Diameter provides a base protocol that can be extended in order to provide AAA (Authentication, Authorization and Accounting) services. The base protocol is not intended to be used by itself, and must be used with a Diameter application. Diameter accounting is part of the base protocol and is therefore not intended for use without a Diameter application.
Diameter can provide two types of service to applications. The first involves authentication and authorization, with optional accounting functionality. The second involves just accounting.
Diameter accounting is based on a server directed model with capabilities for real-time delivery of accounting information. This means that an instance that generates charging data gets information from either the authorization sever (if contacted) or the accounting server regarding the way accounting data is to be forwarded.
The Diameter accounting protocol provides real-time accounting, meaning the processing of information on resource usage within a defined time window. Time constraints are typically imposed to limit financial risk.
Diameter does not presently provide for on-line charging. However, next generation cellular network specify a number of requirements and desirable features for on-line charging. Accounting servers in such networks must be able, for example, to check a subscriber's account for coverage of the requested service prior to execution of that service. The subscriber's account must be debited each time the subscriber uses the services related to that account. Subscriber must also be prevented from accessing chargeable events or services related to their specific accounts once the account credit is exhausted or expired.
It is also desirable to allow a mechanism for indicating to the subscriber the charges to be levied for a chargeable event. Also desirable is the ability to handle multiple charging scenarios, in which different combinations of network entities are simultaneously (or at least during a single call or data generating charges in relation to the subscriber's account.
It is an object of the invention to provide a method of charging to a prepaid account within a network.